The present invention generally relates to an air conditioning system for a motor vehicle; and more particularly to an air conditioning system which ensures the comfort of the passenger compartment without any significant load dependent temperature fluctuations.
In motor vehicles which are equipped with internal combustion engines, the waste heat (lost heat) generated by the internal combustion engine is frequently used for heating the passenger compartment. In an air conditioning system, the waste heat taken from the cooling circuit or the exhaust gas of the internal combustion engine, in an air conditioning system, by at least one heat exchanger, is used for heating an air current which is guided to the passenger compartment.
For some time, however, motor vehicles have increasingly been equipped with fuel consumption optimized driving system concepts. These comprise, for example, a fuel/air mixture supply system with a fuel cut-off during coasting Since, in the case of motor vehicles in coasting phases, no fuel is converted into energy in the internal combustion engine, only frictional heat and stored heat can be used for heating purposes. If the heat for heating purposes is taken from the exhaust gas, the utilization of stored heat is practically completely non-existent.
Thus, it is an object of the present invention to provide an air conditioning arrangement for motor vehicles which ensures the comfort of the passenger compartment without any significant load dependent temperature fluctuations.
Principal advantages of preferred embodiments of the invention are that an air conditioning arrangement for motor vehicles is provided which, for achieving a comfortable temperature, rapidly heats a passenger department to a desired temperature level and maintains this temperature level without any significant load dependent temperature fluctuations.
This is mainly achieved in that, when the heat requirement is increased, a fuel cut-off during a coasting operation of the internal combustion engine is at least temporarily interrupted. In this case, the increased heat requirement may be characterized by a position of a control element affecting the heating of the passenger compartment, particularly by a position in the range of a maximum value (maximal heating).
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.